Retractile telephone cords, commonly referred to as spring cords, are widely used in the communications industry. For example, retractile cords are used to connect the handset and base portions of a telephone instrument. The retractile cord is manufactured with the major portion thereof in the form of a compact helical cord, which may be extended by tension and which will return to the compact form when the tension is relieved. A disclosure of the structure of a retractile cord appears in U.S. Pat. No. 3,037,068 which issued on May 29, 1962 to H. L. Wessel and in U.S. Pat. No. 4,090,763 which issued on May 23, 1978 in the names of W. I. Congdon et al.
At one time, the manufacture of spring cords involved an operator who caused cordage to be fed from a fixed feed-in point and coiled onto a longitudinally moving mandrel. Afterwards, a plurality of the mandrels were stacked in a rack which was conveyed through an oven and then through a cooling chamber. Subsequently, another operator placed each of the mandrels in an apparatus and then caused the removal of each cord from its mandrel in such a manner as to reverse the direction of the helical wind of the cord. This caused the retractile cord to have a permanent and improved retractility.
There was a long felt need for an apparatus that could be used to produce uniformly coiled retractile cords having uniform characteristics at a high rate of production with minimum floor space. That need was satisfied by the invention disclosed and claimed in U.S. Pat. No. 3,988,092 which issued on Oct. 26, 1976 in the names of G. F. Bloxham et al. In accordance with that invention, a leading end of each of a plurality of cordage supplies is advanced into clamping engagement with an associated mandrel of one of a pluraliy of workholders mounted on a conveyor. Cordage is wound in convolutions on each mandrel in a cord-coiling station after which the wound cordage is severed from its supply. Leading and trailing end portions of each cord are clamped to a mandrel in a manner so that they are straight. The group of coiled cords is indexed through a heating zone whereat the mandrels are preheated to supplement subsequent exposure of the wound cords to radiant heat. Simultaneously, the next successive one of the workholders is advanced into the cord-coiling station to have cordage wound on each of its mandrels. The group of coiled cords is advanced through a cooling zone and to a remove-reverse station whereat each cord is removed from its mandrel in a manner to reverse the direction of helical wind and thereby improve the rectractile properties of the cords. After the cords have been removed from the mandrels, the leading and trailing end portions of each cord retain their straight configuration and thereby facilitate termination with a modular plug.
It should be appreciated that the above-described apparatus is designed to manufacture a retractile cord having a fixed length. Significant changes would be necessary to adapt it to the manufacture of different length cords. Moreover, these changes would not be made easily between production runs. What is needed and seemingly what is not available is a method of making a family of lengths of retractile cords. Hopefully, this could be accomplished in cooperation with the above-described apparatus which efficiently manufactures fixed length cords.